The present invention relates generally to multichannel data processing systems and, more particularly, to a method and system for detecting magnetic media and media transport degradation during multichannel recording.
Multichannel tape recording involves the writing and reading of data on more than one track on magnetic tape simultaneously. In the data processing industry, tape devices operate almost exclusively in the multichannel or multi-track environment. Multichannel recording and reading provide a high data transfer rate characterized by high tape speeds, high tape capacities, and decreasing tape thickness.
A tape drive writes data to and reads data from tape. Tape drive controllers generate data recording statistics regarding the quantities of data correction during writing and reading. The tape drive controllers provide the data recording statistics to an attached host computer. Software programs residing at the host computer process the data recording statistics to identify bad tape and/or malfunctioning tape drives. When data is written to and read from tape, the controller typically maintains a tally of various anomalous events that occur during writing (recording) and reading (reproducing). These events are typically categorized by severity and reported separately to the attached host computer for post processing.
The most severe error is a permanent error meaning that the operation that was intended to occur did not occur. The second type of error is a defect and occurs only during recording. A defect indicates that following multiple attempts of the initial recording operation, the data had to be written to another location on the tape for the intended recording operation to be completed. The third type of error is a temporary error. A temporary error indicates that multiple attempts were required for the intended recording or reading operation to be completed. Temporary errors generally indicate debris build up on the head of the tape drive. The debris build up initially causes the recording and reading errors. Multiple attempts of the intended operation cause the debris to break loose allowing the intended operation to be completed successfully. The last type of error is a correction. A correction indicates that the data block being written or read requires some amount of data correcting to correct the error using the embedded error correction code (ECC).
In the past, the quantity of data correction was expected to be low because of the relatively low tape densities. Any elevation in correction counts indicated that error margins were being reduced as more of the ECC was required to make the necessary corrections. Software programs for processing the data recording statistics flag tape for replacement and tape drives for maintenance depending on the data recording statistics. Today, the quantity of corrections is increasing as higher recording densities are being used. The quantity of corrections is increasing because narrower tape tracks are affected easily by asperities in the tape. In the past, asperities were too small to affect the wider tracks used in lower density tape. The increasing quantity of corrections cause high correction counts to be experienced during writing and reading. However, no real error margin has been lost and the ECC can easily handle the larger number of corrections. This causes the correction counts to become uninformative and less useful in determining degradation of tape and tape drives.
Accordingly, it is an object of the present invention to provide a method and system for providing a more refined definition of correction for data recording statistics.
It is another object of the present invention to provide a method and system for generating a count signal indicative of the number of data blocks read from multi-track tape having more than a predetermined threshold of data bytes in error.
It is a further object of the present invention to provide a method and system for generating a degradation signal indicative of tape drive and tape degradation if the data blocks having errors exceeding a predetermined threshold versus the total number of data blocks read from tape exceeds a predetermined ratio.
It is still another object of the present invention to provide a method and system for generating a degradation signal indicative of tape drive degradation when the ratio of data blocks having more than the predetermined number of error data bytes along a single track versus the total number of data blocks read from the tape is above a predetermined ratio.
It is still a further object of the present invention to provide a method and system for generating a tape degradation signal when the ratio of data blocks having more than a predetermined number of tracks for a given data byte in error versus the total number of data blocks read from the tape is above a predetermined ratio.
In carrying out the above objects and other objects, the present invention provides a method for use with a multichannel tape drive for reading data from a tape. The data is recorded on the tape in a plurality of data blocks. Each data block has a plurality of tracks and each track has the same number of data bytes. The method determines degradation of the tape drive and the tape. The method includes reading data blocks on the tape. A determination if more than a predetermined threshold of data bytes are in error for each data block is then made. An error data block count signal indicative of the number of data blocks having more than the predetermined threshold of data bytes being in error is then generated.
Preferably, each data block having more than the predetermined threshold of data bytes being in error is labeled as a corrected data block. The ratio of corrected data blocks versus the total number of data blocks read from the tape is then determined. A degradation signal indicative of degradation is then generated if the ratio of corrected data blocks versus the total number of data blocks read from the tape is above a predetermined ratio.
Preferably, determining if more than a predetermined threshold of data bytes are in error for each data block includes determining if more than a predetermined number of data bytes along a single track are in error for each data block. The degradation signal is then indicative of tape drive degradation if the ratio of data blocks having more than the predetermined number of data bytes along a single track being in error versus the total number of data blocks read from the tape is above a predetermined ratio.
Preferably, determining if more than a predetermined threshold of data bytes are in error for each data block includes determining if more than a predetermined number of tracks for a given data byte are in error for each data block. The degradation signal is then indicative of tape degradation if the ratio of data blocks having more than the predetermined number of tracks for a given data byte being in error versus the total number of data blocks read from the tape is above a predetermined ratio.
In carrying out the above objects and other objects, the present invention further provides a data processing system for determining tape and tape drive degradation in accordance with the method of the present invention. The system includes a multichannel tape drive for reading data blocks from a tape. Each data block has a plurality of tracks and each track has the same number of data bytes. The system further includes a tape drive controller for determining if more than a predetermined threshold of data bytes are in error for each data block. The tape drive controller generates an error data block count signal indicative of the number of data blocks having more than the predetermined threshold of data bytes being in error.
The advantages accruing to the present invention are numerous. The present invention filters out the data blocks that have an acceptable number of errors from the data blocks that have an unacceptable number of errors. This provides a more refined definition of data blocks having errors for statistical data storage analysis.
The above objects and other objects, features, and advantages embodiments of the present invention are readily apparent from the following detailed description of the best mode for carrying out the present invention when taken in connection with the accompanying drawings.